Class: Stream::ConcatenatedStream

Inherits:
WrappedStream show all
Defined in:
lib/stream.rb

Overview

Given a stream of streams. Than a ConcatenatedStream is obtained by concatenating these in the given order. A ConcatenatedStream is created by the methods Stream#concatenate or Stream#concatenate_collected send to a stream of streams or by the method + which concatenats two streams:

((1..3).create_stream + [4,5].create_stream).to_a ==> [1, 2, 3, 4, 5]

Instance Method Summary collapse

Constructor Details

#initialize(streamOfStreams) ⇒ ConcatenatedStream

Creates a new ConcatenatedStream wrapping the stream of streams streamOfStreams.



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# File 'lib/stream.rb', line 510

def initialize(streamOfStreams)
  super
  set_to_begin
end

Instance Method Details

#at_beginning? ⇒ Boolean

Same as at_end? the other way round.



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# File 'lib/stream.rb', line 543

def at_beginning?
  # same algorithm as at_end? the other way round.
  unless @current_stream.at_beginning?
    return false
  end

  until streamOfStreams.at_beginning?
    dir = @dir_of_last_move
    @dir_of_last_move = :backward
    s = streamOfStreams.basic_backward
    next if dir == :forward

    s.set_to_end
    if s.at_beginning?
      next
    else
      @current_stream = s
      return false
    end
  end
  reached_boundary
end

#at_end? ⇒ Boolean

If the current stream is at end, than at_end? has to look ahead to find a non empty in the stream of streams, which than gets the current stream.



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# File 'lib/stream.rb', line 517

def at_end?
  unless @current_stream.at_end?
    return false
  end

  until streamOfStreams.at_end?
    dir = @dir_of_last_move
    @dir_of_last_move = :forward
    s = streamOfStreams.basic_forward
    # if last move was backwards, then @current_stream is
    # equivalent to s. Move to next stream.
    next if dir == :backward

    s.set_to_begin
    if s.at_end? # empty stream?
      next # skip it
    else
      @current_stream = s
      return false # found non empty stream
    end
  end # until
  reached_boundary # sets @dir_of_last_move and @current_stream
end

#basic_backward ⇒ Object

Returns the previous element of @current_stream. at_beginning? ensured that there is one.



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# File 'lib/stream.rb', line 582

def basic_backward
  @current_stream.basic_backward
end

#basic_forward ⇒ Object

Returns the next element of @current_stream. at_end? ensured that there is one.



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# File 'lib/stream.rb', line 576

def basic_forward
  @current_stream.basic_forward
end

#set_to_begin ⇒ Object 



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# File 'lib/stream.rb', line 566

def set_to_begin
  super; reached_boundary
end

#set_to_end ⇒ Object 



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# File 'lib/stream.rb', line 570

def set_to_end
  super; reached_boundary
end